1. Field of the Invention
The present invention is directed to silicone copolymers containing oxygen sensitive compounds. More particularly, this invention is directed to silicone polyurethane copolymers covalently bonded to phosphorescent dye compounds which are useful in fiber optic probes for the in vivo measurement of physiological gases.
2. Description of the Prior Art
The measurement of the partial pressure of oxygen in blood and tissue is important for the diagnosis of disease and the monitoring of patients during surgical and intensive care procedures. The use of fiber optic probes employing luminescence quenching for such biomedical measurements has become very popular because these probes are easy to insert, involve no electrical hazards, and are economical to produce.
In a fiber optic probe employing luminescence quenching, light from a suitable source is transmitted through long, thin, optically conducting flexible fibers of glass, plastic, or other transparent material to a receptor terminal containing a luminescent dye on an oxygen permeable support medium. The light causes the dye to luminesce and oxygen present in the blood or tissue quenches the luminescence. The light is then returned along the optical fiber to a light measuring instrument containing photomultiplier or photodiode tubes and an electronic computing circuit for processing. A number of types of fiber optic probes employing luminescence quenching are known.
U.S. Pat. No. 4,714,770, issued to Huse et. al., discloses a dye-containing silane composition wherein a fluorescent polynuclear aromatic dye and a silane derivative are bonded through a urethane linkage. The dye-containing silane composition may then be linked to a polysiloxane, through a silicon polymer reactive substituent on the silane derivative, to form a dye-containing polysiloxane.
U.S. Pat. No. 4,868,251, issued to Reich et. al., discloses an ultraviolet light absorbing silicon composition prepared by covalently bonding, by platinum catalysis, a hydride functional silicone base polymer with an ultraviolet light absorbing compound containing a terminal double bond.
U.S. Pat. No. 4,866,152, issued to Lo, discloses fluorescent organosilicon compounds prepared by covalently bonding an aminoalkylfunctional organosilicon compound with a fluorescent organoaldehyde or a fluorescent organosulfonic acid by condensation.
U.S. Pat. No. 4,719,281, issued to Choe, discloses polymers consisting of enediamine-quinoid derivatives bonded to polyurethane groups or organosiloxyl groups.
U.S. Pat. No. 4,361,691, issued to Yajima et. al., discloses a method for preparing a heat resistant polymer which comprises reacting a diamine with a metallosiloxane compound containing siloxane bonds and metalloxane bonds. The metal may be titanium, zirconium, vanadium, phosphorous, aluminum, iron, chromium, cobalt, nickel, germanium, tin, arsenic, magnesium, lead, or antimony.
While a number of fiber-optic probe devices have been reported, none of these devices are entirely satisfactory. Many luminescent dyes are fluorescent dyes which require expensive instrumentation to employ because such dyes have short emission lifetimes and are not highly sensitive to quenching. Most fluorescent dyes are also sensitive to several anesthetic gases, often present in patients requiring tissue oxygenation monitoring. Furthermore, the permeability and solubility of the physiological gas in the support medium for the dye is not always optimal for the particular instrumentation employed. Accordingly, fiber optic probes containing dyes which are inexpensive to use and support media which can be altered to vary gas permeability and solubility would be highly desirable. The present invention provides such improved polymeric support media containing dyes for use in fiber optic probes employing luminescence quenching and methods by which such fiber optic probe materials can be made.